FBL5N document attachments detection

hi all! i'm very new with SAP and i really need help on this one.

im trying to create a custom program that will detect if sales documents found on transaction FBL5N contain attachments or not. the FB03 transaction has a display attachment option and i was wondering on what table it retrieves the information of what attachment it contains.

i have tried table SOOD but i could not find any relation with tables BSEG or BSIS.

any input would really go a long way.

thanks!

chad